Abstract: For cross-linked polyethylene (XLPE) insulated HVDC submarine cables, a theoretical analysis of their transmission equations and the corresponding series impedance matrix and shunt admittance matrix was conducted, with both analytical calculation and numerical modeling simulation methods studied. A calculation model and method for the key electrical parameters of DC subsea cables were established. In order to compare and analyze the applicability of these methods with two numerical simulations and an analytical calculation, the XLPE insulated HVDC submarine cable with voltage level of ±525 kV was taken as examples to calculate its electrical parameters and their change regularity under different harmonic frequencies, which could provide a research reference for design and characteristic analysis of XLPE insulated HVDC submarine cables in power transmission system.